Fabrication method and fabrication apparatus for backlight source, display device, and a display system

ABSTRACT

A method for fabricating a backlight source includes determining an n-step MacAdam ellipse in a uniform chromaticity diagram, where n is an integer smaller than or equal to 3; and fabricating the backlight source according to chromaticity coordinates within the n-step MacAdam ellipse to cause chromaticity coordinates of light emitted from different ones of light-emitting diodes of the backlight source to be within the n-step MacAdam ellipse.

CROSS-REFERENCE TO RELATED APPLICATION

This PCT patent application claims priority to Chinese PatentApplication No. 201710200377.5, filed on Mar. 30, 2017, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to the field of displaytechnologies and, more particularly, to a fabrication method and afabrication apparatus for a backlight source, a display device, and adisplay system.

BACKGROUND

Generally, a backlight source in a display device may include aplurality of LEDs, and light emitted by the LEDs can penetrate a displaypanel in the display device.

In the conventional technology, light emitted from different LEDs hasdifferent luminance and chrominance. When a display device or a displaysystem displays images, light emitted from different regions of thedisplay device or the display system has different luminance andchrominance. Thus, an image display performance is poor.

SUMMARY

In one aspect, the present disclosure provides a method for fabricatinga backlight source. The method includes determining an n-step MacAdamellipse in a uniform chromaticity diagram, and fabricating the backlightsource according to chromaticity coordinates within the n-step MacAdamellipse. n is an integer smaller than or equal to 3, and chromaticitycoordinates of light emitted from different ones of light-emittingdiodes of the backlight source are within the n-step MacAdam ellipse.

Another aspect of the present disclosure provides a fabricationapparatus for a backlight source. The fabrication apparatus includes adetermination device and a fabrication device. The determination deviceincludes a processor configured to determine an n-step MacAdam ellipsein a uniform chromaticity diagram, where n is an integer smaller than orequal to 3. The fabrication device is configured to fabricate thebacklight source according to chromaticity coordinates in the n-stepMacAdam ellipse to cause chromaticity coordinates of light emitted fromdifferent ones of light-emitting diodes of the backlight source to bewithin the n-step MacAdam ellipse.

BRIEF DESCRIPTION OF THE FIGURES

The following drawings are merely examples for illustrative purposesaccording to various disclosed embodiments and are not intended to limitthe scope of the present disclosure.

FIG. 1 illustrates a flow chart of an exemplary fabrication method foran exemplary backlight source according to various disclosed embodimentsof the present disclosure;

FIG. 2 illustrates a flow chart of another exemplary fabrication methodfor an exemplary backlight source according to various disclosedembodiments of the present disclosure;

FIG. 3 illustrates a schematic view of an exemplary uniform chromaticitydiagram according to various disclosed embodiments of the presentdisclosure;

FIG. 4 illustrates schematic views of exemplary initial ellipsesaccording to various disclosed embodiments of the present disclosure;

FIG. 5 illustrates a schematic view of an exemplary chromaticity-regionquadrilateral according to various disclosed embodiments of the presentdisclosure;

FIG. 6 illustrates schematic views of exemplary chromaticity-regionquadrilaterals according to various disclosed embodiments of the presentdisclosure;

FIG. 7 illustrates a schematic view of a display panel of an advancedsuper dimension switch (ADS) mode;

FIG. 8 illustrates a block diagram of an exemplary fabrication apparatusfor fabricating an exemplary backlight source according to variousdisclosed embodiments of the present disclosure;

FIGS. 9A and 9B illustrate block diagrams of an exemplary determinationdevice according to various disclosed embodiments of the presentdisclosure;

FIG. 10A illustrates a schematic view of an exemplary display deviceaccording to various disclosed embodiments of the present disclosure;and

FIG. 10B illustrates a schematic view of an exemplary display systemaccording to various disclosed embodiments of the present disclosure.

DETAILED DESCRIPTION

Exemplary embodiments of the disclosure will now be described in moredetail with reference to the drawings. It is to be noted that, thefollowing descriptions of some embodiments are presented herein forpurposes of illustration and description only, and are not intended tobe exhaustive or to limit the scope of the present disclosure.

The aspects and features of the present disclosure can be understood bythose skilled in the art through the exemplary embodiments of thepresent disclosure further described in detail with reference to theaccompanying drawings.

A light-emitting diode (LED) may have a high visibility and a low powerconsumption, and may often be used as a backlight source or a portionofa backlight source in a display device. In order to realize alarge-area display, a plurality of display devices may be assembledtogether to form a display system including the plurality of displaydevices.

FIG. 1 illustrates a flow chart of an exemplary fabrication method foran exemplary backlight source according to various disclosed embodimentsof the present disclosure. With reference to FIG. 1, the fabrication isdescribed below.

At S101, an n-step MacAdam ellipse is determined in a uniformchromaticity diagram, where n is an integer smaller than or equal to 3.A MacAdam ellipse is an elliptical region on a chromaticity diagram thatcontains colors that are indistinguishable to the average human eye,from the color at a center of the ellipse. MacAdam ellipses can bedescribed as having “steps,” which represent “standard deviations.” Forexample, a point on a boundary of a 1-step MacAdam ellipse around acenter of the ellipse represents 1 standard deviation from the center ofthe ellipse. A point on a boundary of an n-step MacAdam ellipse around acenter of the ellipse represents n standard deviation from the center ofthe ellipse.

At S102, the backlight source is fabricated according to chromaticitycoordinates within the n-step MacAdam ellipse, such that a chromaticitycoordinate of light emitted from each light-emitting diode of thebacklight source is within the n-step MacAdam ellipse.

In the disclosed fabrication method for the backlight source, thebacklight source may be fabricated according to chromaticity coordinateswithin a MacAdam ellipse that is lower than or equal to 3-step, suchthat light emitted from different light-emitting diode of the backlightsource may have chromaticity coordinates located within the MacAdamellipse that is lower than or equal to 3-step. A human eye cannotdistinguish light of two different chromaticity coordinates locatedwithin a same 3-step MacAdam ellipse. Thus, even if different LEDs ofthe backlight source emit light of different luminances andchrominances, the human eye cannot distinguish the different luminancesand chrominances. Accordingly, when a display device consistent withembodiments of the disclosure displays an image, the light emitted fromdifferent regions of the display device may have luminance andchrominance that appear the same to the human eye, and a displayperformance of the display devices can be improved.

FIG. 2 illustrates a flow chart of another exemplary fabrication methodfor an exemplary backlight source according to various disclosedembodiments of the present disclosure. With reference to FIG. 2, thefabrication method is described below.

At S201, a target color temperature of a display device including thebacklight source is determined.

In some embodiments, each type of display device may correspond to apreset color temperature, and, at S201, the type of the display deviceincluding the backlight source to be fabricated may be determined, andthen the target color temperature of the display device may bedetermined according to the determined type of the display device.

At S202, an intersection of an isothermal line segment of the targetcolor temperature and a Planckian locus is determined in a uniformchromaticity diagram. A Planckian locus is a path or locus that thecolor of a black body may take in a chromaticity diagram as theblackbody temperature changes.

FIG. 3 illustrates a schematic view of an exemplary uniform chromaticitydiagram according to various disclosed embodiments of the presentdisclosure. As shown in FIG. 3, an abscissa, i.e., a lateral-coordinateand an ordinate, i.e., a vertical-coordinate, in the uniformchromaticity diagram constitute a chromaticity coordinate in the uniformchromaticity diagram. The color temperature may be related to ablackbody radiation temperature. A point in the uniform chromaticitydiagram, i.e., a point corresponding to an abscissa and an ordinate, maycorrespond to a light color, i.e., a chromaticity. As the temperature ofthe blackbody rises from a lower temperature to an infinitely-hightemperature, in the chromaticity diagram, the chromaticity coordinate ofthe blackbody chromaticity may form a continuous curve, i.e., aPlanckian locus.

In addition, a plurality of isothermal line segments may exist in theuniform chromaticity diagram, and each isothermal line segment mayrepresent a color temperature. For example, FIG. 3 illustratesisothermal line segments representing color temperatures of 1500K (1500Kelvin), 2000K, 2500K, 3000K, 4000K, 6000K, 10000K and infinity (∞) K.

In the process of S202, the isothermal line segment corresponding to thetarget color temperature determined in the process of S201 can be foundin the uniform chromaticity diagram, and the intersection of theisothermal line segment and the Planckian locus can be determined. Forexample, if the target color temperature determined in the process ofS201 is 6000K, the intersection A, i.e., the chromaticity coordinate ofthe intersection A, of the isothermal line segment of 6000K and thePlanckian locus can be determined in the process of S202.

At S203, according to the isothermal line segment and the intersection,an n-step MacAdam ellipse is determined. The intersection is within then-step MacAdam ellipse and two endpoints of the isothermal line segmentare located on the n-step MacAdam ellipse. In some embodiments, n is aninteger smaller than or equal to 3.

After the isothermal line segment of the target color temperature, andthe intersection of the isothermal line segment of the target colortemperature and the Planckian locus, are determined, at least oneinitial ellipse can be determined according to the isothermal linesegment of the target color temperature and the intersection of theisothermal line segment of the target color temperature and thePlanckian locus. Each initial ellipse is centered at the intersection ofthe isothermal line segment of the target color temperature and thePlanckian locus, and the two endpoints of the isothermal line segment ofthe target color temperature are on the corresponding initial ellipse.For example, when the target color temperature is 6000K and theintersection of the isothermal line segment of the target colortemperature and the Planckian locus is point A, a plurality of initialellipses B can be determined, as shown in FIG. 4. Each initial ellipsehas a center point at the intersection A, and the two endpoints C1 andC2 of the isothermal line segment of the target color temperature arelocated on each initial ellipse B.

In some embodiments, a plurality of MacAdam ellipses (not shown in FIG.3) may exist in the uniform chromaticity diagram. After at least oneinitial ellipse is determined, the determined at least one initialellipse may be matched with an m-step MacAdam ellipse in the uniformchromaticity diagram, such that a largest one of the at least oneinitial ellipse that contains the m-step MacAdam ellipse may bedetermined, where n≤m≤7. Such a largest one of the at least one initialellipse is also referred to as a largest initial ellipse containing them-step MacAdam ellipse. For example, assume three initial ellipses intotal are determined, a first initial ellipse contains a 7-step MacAdamellipse, a second initial ellipse contains a 5-step MacAdam ellipse, anda third initial ellipse does not contain a MacAdam ellipse that is lowerthan or equal to 7-step. Further, assume the first initial ellipse has alarger area than the second initial ellipse, and the second initialellipse has a larger area than the third initial ellipse. Accordingly,it can be determined that the first initial ellipse and the secondinitial ellipse each is an initial ellipse containing a MacAdam ellipselower than or equal to 7-step. Further, because the first initialellipse is larger than the second initial ellipse, it can be determinedthat the first initial ellipse is a largest one of the at least oneinitial ellipse that contain a MacAdam ellipse lower than or equal to7-step.

Further, after the largest initial ellipse is determined, achromaticity-region quadrilateral can be determined according to thelargest initial ellipse. Four vertices of the chromaticity-regionquadrilateral can be, for example, the two endpoints of the isothermalline segment, a point on the largest initial ellipse corresponding to aminimum abscissa of the largest initial ellipse in the uniformchromaticity diagram, and a point on the largest initial ellipsecorresponding to a maximum abscissa of the largest initial ellipse inthe uniform chromaticity diagram, respectively. Then, the n-step MacAdamellipse is determined in the chromaticity-region quadrilateral. In someembodiments, n may be an integer smaller than or equal to 3. If n isequal to 3, the n-step MacAdam ellipse may have a span less than orequal to approximately 0.01 in the lateral-axis direction of the uniformchromaticity diagram, and may have a span less than or equal toapproximately 0.00978 in the vertical-axis direction of the uniformchromaticity diagram.

For example, as shown in FIG. 5, assuming that point D1 is the point onthe largest initial ellipse B1 corresponding to a minimum abscissa ofthe largest initial ellipse B1 in the uniform chromaticity diagram,point D2 is the point on the largest initial ellipse B1 corresponding toa maximum abscissa of the largest initial ellipse B1 in the uniformchromaticity diagram, and point C1 and point C2 are the two endpoints ofthe isothermal line segment of the target color temperature, thenquadrilateral E can be the chromaticity-region quadrilateral.

Similarly, for target temperatures of 7250K, 6500K, 5700K, 5000K, 4500K,4000K, 3500K, 3000K, and 2700K, the identified chromaticity-regionquadrilaterals are shown in FIG. 6, respectively.

At S204, the backlight source is fabricated according to chromaticitycoordinates within the n-step MacAdam ellipse, such that light emittedfrom each light-emitting diode in the backlight source has achromaticity coordinate located within the n-step MacAdam ellipse.

After the n-step MacAdam ellipse is determined in thechromaticity-region quadrilateral, the backlight source can befabricated according to the chromaticity coordinates within the n-stepMacAdam ellipse. That is, a point within the n-step MacAdam ellipse maybe selected, and a light-emitting diode in the backlight source may befabricated according to a chromaticity coordinate of the selected point,such that a chromaticity coordinate of light emitted from thelight-emitting diode may be same as or close to the chromaticitycoordinate of the selected point.

In some embodiments, the backlight source may include a plurality oflight-emitting diodes. The plurality of light-emitting diodes mayinclude at least two light-emitting diodes that emit white light ofdifferent wavelengths, and further the at least two light-emittingdiodes may have different red light components, different green lightcomponents, and different blue light components in the white light. Thatis, when the at least two light-emitting diodes are fabricated, at leasttwo different points within the n-step MacAdam ellipse may be selected,and the at least two light-emitting diodes may be fabricated accordingto chromaticity coordinates of the at least two different points,respectively.

In some embodiments, light emitted from the backlight source may be asum of red light, green light, and blue light emitted from the backlightsource. Further, the red light emitted from the backlight source mayinclude red light component of white light emitted from eachlight-emitting diode. The green light emitted from the backlight sourcemay include green light component of white light emitted from eachlight-emitting diode. The blue light emitted from the backlight sourcemay include blue light component of white light emitted from eachlight-emitting diode. That is, light emitted from the plurality oflight-emitting diodes in the backlight source is coupled to form coupledlight. Thus, as long as the coupled light has a color satisfies a presetcondition, it is not necessary for the light from each individuallight-emitting diode to satisfy the preset condition. In other words, aslong as the coupled light has a color that is needed, the light fromeach individual light-emitting diode does not have to be the color thatis needed.

Further, in order to improve a uniformity of the light emitted from thebacklight source, each two neighboring light-emitting diodes in the atleast two light-emitting diodes may be configured to emit white light ofdifferent wavelengths. For example, the at least two light-emittingdiodes may include at least one first light-emitting diode and at leastone second light-emitting diode. The at least two light-emitting diodesmay be arranged, for example, in the order of a first light-emittingdiode, a second light-emitting diode, a first light-emitting diode, asecond light-emitting diode, and so on. Further, wavelengths of whitelight emitted from each two neighboring light-emitting diodes in the atleast two light-emitting diodes may be different.

Because a chromaticity coordinate of white light perceived by a humaneye may be located below the Planckian locus, among a plurality ofchromaticity coordinates of white light emitted from the plurality oflight-emitting diodes, relatively more chromaticity coordinates may beconfigured to be below the Planckian locus than above the Planckianlocus. That is, assuming, among the plurality of chromaticitycoordinates of white light emitted from the plurality of light-emittingdiodes in the uniform chromaticity diagram, the number of chromaticitycoordinates located on a side of the Planckian locus near to the lateralaxis of the uniform chromaticity diagram is referred to as x, and thenumber of chromaticity coordinates located on another side of thePlanckian locus farther away from the lateral axis of the uniformchromaticity diagram is referred to as y, then x may be greater than y.

In addition, the isothermal line segment of the target color temperaturecorresponding to the display device including the backlight source maypass through the n-step MacAdam ellipse. Thus, color temperatures ofchromaticity coordinates in the n-step MacAdam ellipse may be same as orclose to the target color temperature. Accordingly, color temperaturesof light emitted by the fabricated backlight source may be the same asor close to the target color temperature.

FIG. 7 illustrates a schematic view of a display panel of an advancedsuper dimension switch (ADS) mode. As shown in FIG. 7, when a turn-onvoltage is not applied at two ends of a liquid crystal, a polarizerplate may have a transmission axis parallel to an orientation of theliquid crystal, and incident light may be blocked by the crossedpolarizer plate. Accordingly, the display panel is in a normally-blackmode. When a transverse electric field is formed between the electrodes,e.g., when a turn-on voltage is applied at two ends of the liquidcrystal, the liquid crystal may twist along a direction of the electricfield, such that the light can pass through the crossed polarizerplates, to achieve a display function of the display panel. When thedisplay panel displays, light may be influenced by optical anisotropy ofthe liquid crystal, and birefringent dispersion may occur during lighttransmission in the liquid crystal, thereby influencing luminance andchrominance of light emitted from the display panel.

Table 1 shows parameters of two display panels (display panel 1 anddisplay panel 2) having same color film substrates.

TABLE 1 Display Display Parameter Panel 1 Panel 2 Difference Wx 0.2750.28 −0.005 Wy 0.281 0.288 −0.007 Rx 0.632 0.633 −0.001 Ry 0.346 0.346 0Gx 0298 0.298 0 Gy 0.634 0.634 0 Bx 0.15 0.149 0.001 By 0.058 0.06−0.002 Luminance (nit) 558 555 3 Color Temperature (K) 10992 9982 1009Color Gamut 74.3 74.3 0

As shown in Table 1, parameters of a display panel include a white-dotchromaticity coordinate (Wx, Wy) at the 255 grayscale value, aluminance, a color temperature, a color gamut, and chromaticitycoordinates of red color (Rx, Ry), green color (Gx, Gy), and blue color(Bx, By) determined according to a display status of the display panel.According to Table 1, the birefringence dispersion of the liquid crystalhas a relatively large influence on the color temperature. However, inthe display device including the backlight source fabricated by thefabrication method of the present disclosure, color of light emittedfrom different light-emitting diodes of the backlight source may belocated within the n-step MacAdam ellipse, and a human eye cannotdistinguish a difference between chromaticity coordinates within then-step MacAdam ellipse. Thus, even if the liquid crystal in the displaypanel causes an influence on the light due to the birefringencedispersion, the human eye cannot distinguish the difference in the lightemitted from the two display devices caused by the influence of thebirefringence dispersion.

In some embodiments, the backlight source fabricated by the fabricationmethod of the present disclosure can be applicable to a single displaydevice. In some other embodiments, the backlight source fabricated bythe fabrication method of the present disclosure can includes aplurality of backlight sub-sources, each backlight sub-source can beapplicable to a single display device, and the plurality of backlightsub-sources, i.e., the backlight source can be applicable to a pluralityof display devices that can be assembled into a display system.Accordingly, a display system having a relatively large area can beformed by assembling a plurality of display devices. Experimentalresults show that, for backlight sources of the two display systems, adifference in color temperatures can be controlled within approximately500K, a chromaticity difference can be controlled within approximately0.008, a luminance difference at 0-grayscale can be controlled withinapproximately 70%, and a luminance difference at 255-grayscale can becontrolled within approximately 95%.

Further, before the backlight source is fabricated, a virtual model ofthe plurality of light-emitting diodes in the backlight source may bebuilt, and each light-emitting diode in the built virtual model can beconfigured to emit light of preset luminance and a preset chromaticitycoordinate. The chromaticity coordinate may be determined within then-step MacAdam ellipse, and the determined chromaticity coordinatewithin the n-step MacAdam ellipse may have a boundary-point floatingrange that allows an error of approximately ±0.0045. Further, a voltageapplied to the light-emitting diode may be controlled when thelight-emitting diode emits light, such that light emitted by theplurality of light emitting-diodes can be coupled to form the neededlight. Chromaticity coordinates of light emitted from the light-emittingdiodes of the fabricated backlight source and chromaticity coordinatesof light emitted from the light-emitting diodes of the virtual model maydiffer by approximately ±0.002. Peaks of light emitted from thelight-emitting diodes of the fabricated backlight source may differ frompeaks of light emitted from the light-emitting diodes of the virtualmodel by less than approximately 4 nm. Luminance of light emitted fromthe light-emitting diodes of the fabricated backlight source may differfrom luminance of light emitted from the light-emitting diodes of thevirtual model by approximately ±5%. Voltages needed to control thelight-emitting diodes of the fabricated backlight source to emit lightmay be different from voltages needed to control the light-emittingdiodes of the virtual model by approximately ±0.05 volts.

A concentration of a fluorescent powder needed for fabricating thelight-emitting diodes can be determined by experiments. That is, eachtime, after the light-emitting diodes are fabricated, the concentrationof the fluorescent powder used for fabricating the light-emitting diodescan be recorded. The concentrations of the fluorescent powder used forfabricating the light-emitting diodes at different times can be comparedwith each other, and a suitable concentration of the fluorescent powdercan be selected.

After the light-emitting diodes are fabricated, the light-emittingdiodes can be tested to determine whether the light-emitting diodes meeta preset condition. That is, the light-emitting diodes can be tested todetermine whether chromaticity coordinates of the light emitted by thelight-emitting diodes are located within the n-step MacAdam ellipse.Further, the light-emitting diodes can be tested to determine whetherluminance of light from the fabricated backlight source meets a presetcondition. If the light-emitting diodes do not meet the presetcondition, various parameters for fabricating the light-emitting diodesmay be adjusted. The light-emitting diodes may be fabricated againaccording to the adjusted parameters, until the backlight source, i.e.,the light-emitting diodes, meets the preset condition.

In the disclosed fabrication method for the backlight source, thebacklight source may be fabricated according to chromaticity coordinateswithin a MacAdam ellipse that is lower than or equal to 3-step, suchthat light emitted from different light-emitting diodes of the backlightsource may have chromaticity coordinates located within the MacAdamellipse that is lower than or equal to 3-step. The human eye cannotdistinguish light of two different chromaticity coordinates locatedwithin a same 3-step MacAdam ellipse. Thus, even if different LEDs inthe backlight source emit light of different luminance and chrominance,the human eye cannot distinguish the difference. Accordingly, when thedisplay device displays an image, light emitted from different regionsof the display device may have luminance and chrominance that appear thesame to the human eye, and a display performance of the display devicesmay be improved.

FIG. 8 illustrates a block diagram of an exemplary fabrication apparatusfor fabricating an exemplary backlight source according to variousdisclosed embodiments of the present disclosure. As shown in FIG. 8, thefabrication apparatus 80 for fabricating the backlight source includes adetermination device 801 and a fabrication device 802.

The determination device 801 is configured to determine an n-stepMacAdam ellipse in a uniform chromaticity diagram, where n is an integersmaller than or equal to 3.

The fabrication device 802 is configured to fabricate the backlightsource according to chromaticity coordinates within the determinedn-step MacAdam ellipse, such that chromaticity coordinates of lightemitted from different light-emitting diodes of the backlight source arelocated within the n-step MacAdam ellipse.

In the fabrication apparatus of the present disclosure for fabricating abacklight source, a fabrication device may fabricate the backlightsource according to chromaticity coordinates within an MacAdam ellipsethat is lower than or equal to 3-step, such that chromaticitycoordinates of light emitted from different light-emitting diodes of thebacklight source may be located within the MacAdam ellipse that is lowerthan or equal 3-step. A human eye cannot distinguish light of twodifferent chromaticity coordinates located within a same 3-step MacAdamellipse. Thus, even if different LEDs in the backlight source emit lightof different luminances and chrominances, the human eye cannot tell thedifference. Accordingly, when the display device displays images, lightemitted from different regions of the display device may have luminancesand chrominances that appear the same to the human eye, and a displayperformance of the display device may be improved.

FIG. 9A illustrates a block diagram of an exemplary determination deviceaccording to various disclosed embodiments of the present disclosure. Asshown in FIG. 9A, the determination device 801 includes a firstdetermining unit 8011, a second determining unit 8012, and a thirddetermination unit 8013.

The first determination unit 8011 is configured to determine a targetcolor temperature of the display device including the backlight source.

The second determination unit 8012 is configured to determine anintersection of an isothermal line segment of the target colortemperature and a Planckian locus on a uniform chromaticity diagram.

The third determination unit 8013 is configured to determine an n-stepMacAdam ellipse according to the isothermal line segment and theintersection, where the intersection is located within the n-stepMacAdam ellipse, and two endpoints of the isothermal line segment arelocated on the n-step MacAdam ellipse.

In some embodiments, the third determination unit 8013 may further beconfigured to determine at least one initial ellipse according to theisothermal line segment and the intersection. The initial ellipse has acenter point at the intersection, and the two endpoints of theisothermal line segments are located on the at least one initialellipse. The third determination unit 8013 may further be configured tomatch the at least one initial ellipse with an m-step MacAdam ellipse(n≤m≤7) in the uniform chromaticity diagram to determine a largestinitial ellipse that contains the m-step MacAdam ellipse from the atleast one initial ellipse, and to determine a chromaticity-regionquadrilateral according to the largest initial ellipse. Thechromaticity-region quadrilateral has four vertices, two of which arethe two endpoints of the isothermal line segment, and the other two ofwhich are a point on the largest initial ellipse corresponding to aminimum abscissa of the largest initial ellipse in the uniformchromaticity diagram and a point on the largest initial ellipsecorresponding to a maximum abscissa of the largest initial ellipse inthe uniform chromaticity diagram, respectively. The third determinationunit 8013 may be further configured to determine an n-step MacAdamellipse in the chromaticity-region quadrilateral.

In some embodiments, the plurality of light-emitting diodes may includeat least two light-emitting diodes that emits white light of differentwavelengths, and further the at least two light-emitting diodes may havedifferent red light components, different green light components, anddifferent blue light components in the emitted white light.

In some embodiments, each two neighboring light-emitting diodes in theat least two light-emitting diodes may emit white light of differentwavelengths.

In some embodiments, among a plurality of chromaticity coordinates ofwhite light emitted from the plurality of light-emitting diodes in theuniform chromaticity diagram, the number of chromaticity coordinateslocated on one side of the Planckian locus near to the lateral axis ofthe uniform chromaticity diagram may be larger than the number ofchromaticity coordinates located on another side of the Planckian locusfarther away from the lateral axis of the uniform chromaticity diagram.

In the fabrication apparatus of the present disclosure for fabricating abacklight source, a fabrication device may fabricate the backlightsource according to chromaticity coordinates within an MacAdam ellipsethat is lower than or equal to 3-step, such that chromaticitycoordinates of light emitted from different light-emitting diode of thebacklight source are located within the MacAdam ellipse that is lowerthan or equal to 3-step. A human eye cannot distinguish light of twodifferent chromaticity coordinates located in a same 3-step MacAdamellipse. Thus, even if different LEDs in the backlight source emit lightof different luminances and chrominances, the human eye cannot see thedifference. Accordingly, when a display device including the backlightsource displays an image, light emitted from different regions of thedisplay device may have luminances and chrominances that appear the sameto the human eye, and a display performance of the display device may beimproved.

FIG. 9B illustrates a block diagram of another exemplary hardwareconfiguration of the exemplary determination device 801 according tovarious disclosed embodiments of the present disclosure. As shown inFIG. 9B1, the determination device 801 includes a processor 982 and amemory 983. The memory 983 stores instructions for execution by theprocessor 982 to perform a method consistent with the presentdisclosure. In some embodiments, the processor 982 may include, forexample, a microprocessor. In some embodiments, the memory 983 mayinclude, for example, a read only memory (ROM) or a random access memory(RAM).

The present disclosure provides a display device. FIG. 10A illustrates aschematic view of an exemplary display device 900 according to variousdisclosed embodiments of the present disclosure. As shown in FIG. 10A,the display device 900 includes a backlight source 901 and a displaypanel 902. The backlight source 901 includes a plurality of LEDs 903,and provides light to the display panel 902. The backlight source 901can be fabricated, for example, by a fabrication method consistent withthe present disclosure, such as the fabrication method described abovein connection with FIG. 1 or FIG. 2. The backlight source can bearranged on, for example, a light entry side of the display panel. FIG.10A shows an edge-lit display device as an example, in which thebacklight source is arranged at an edge of the display panel. A displaydevice consistent with embodiments of the disclosure can include abacklit display device, in which the backlight source is arranged at theback of the display panel.

The display device can be, for example, a liquid crystal display device,an electronic paper, a mobile phone, a tablet computer, a televisionset, a monitor, a notebook computer, a digital photo frame, a navigator,or any product or component having a display function.

In the display device of the present disclosure, chromaticitycoordinates of light emitted from different light-emitting diodes of thebacklight source may be located within a same MacAdam ellipse that islower than or equal to 3-step. A human eye cannot distinguish light oftwo different chromaticity coordinates located in a same 3-step MacAdamellipse. Thus, even if different LEDs in the backlight source emit lightof different luminances and chrominances, the human eye cannot tell thedifference. Accordingly, when the display device displays an image,light emitted from different regions of the display device may haveluminances and chrominances that appear the same to the human eye, and adisplay performance of the display device may be improved.

The present disclosure provides a display system. The display system caninclude a plurality of display devices consistent with the presentdisclosure that are assembled together. Each of the plurality of displaydevices can include a backlight source and a display panel, and thebacklight source can be fabricated, for example, by a fabrication methodconsistent with the present disclosure, such as the fabrication methoddescribed above in connection with FIG. 1 or FIG. 2. The backlightsource can be arranged on, for example, a light entry side of thedisplay panel.

FIG. 10B illustrates a schematic view of an exemplary display system Xaccording to various disclosed embodiments of the present disclosure. Asshown in FIG. 10B, the display system X includes a plurality of displaydevices Y, which are arranged in an array and assembled to form thedisplay system X. As such, a display area of the display system X isequal to or close to a sum of display areas of the plurality of displaydevices Y, and the display system X can have a relatively large displayarea. The manner of assembling the plurality of display devices shown inFIG. 10B is merely for illustrative purposes, and does not limit thescope of the present disclosure. In the present disclosure, theplurality of display devices can be arranged and assembled in othermanners according to various application scenarios, which are notlimited.

In the display system of the present disclosure, in a backlight sourceof each display device, chromaticity coordinates of light emitted fromdifferent light-emitting diodes may be located within a same MacAdamellipse that is lower than or equal to 3-step. A human eye cannotdistinguish light of two different chromaticity coordinates located in asame 3-step MacAdam ellipse. Thus, even if different LEDs in thebacklight source emit light of different luminances and chrominances,the human eye cannot tell the difference. Accordingly, when the displaysystem displays an image, the light emitted from different regions ofthe display system may have luminances and chrominances that appear thesame to the human eye, and a display performance of the display systemmay be improved.

The present disclosure provides a fabrication method and a fabricationapparatus for a backlight source, a display device, and a displaysystem. The fabrication method may include determining an n-step MacAdamellipse in a uniform chromaticity diagram (n is an integer smaller thanor equal to 3), and fabricating the backlight source according tochromaticity coordinates in the n-step MacAdam ellipse, such thatchromaticity coordinates of light emitted from different light-emittingdiodes in the backlight source may be located within the n-step MacAdamellipse. The present disclosure may improve image display performance.

In the present disclosure, method embodiments and correspondingapparatus embodiments/device embodiments/system embodiments can bereferred to each other, which is not limited in the present disclosure.The sequence of the steps of method embodiments of the presentdisclosure can be adjusted appropriately, and the steps can be added orremoved appropriately according to various application scenarios, all ofwhich are within the scope of the present disclosure.

The foregoing description of the embodiments of the disclosure has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the disclosure to the precise formor to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent to personsskilled in this art. The embodiments are chosen and described in orderto explain the principles of the technology, with various modificationssuitable to the particular use or implementation contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto in which all terms are meant in their broadestreasonable sense unless otherwise indicated. Therefore, the term “thedisclosure,” “the present disclosure,” or the like does not necessarilylimit the claim scope to a specific embodiment, and the reference toexemplary embodiments of the disclosure does not imply a limitation onthe invention, and no such limitation is to be inferred. Moreover, theclaims may refer to “first,” “second,” etc., followed by a noun orelement. Such terms should be understood as a nomenclature and shouldnot be construed as giving the limitation on the number of the elementsmodified by such nomenclature unless specific number has been given. Anyadvantages and benefits described may or may not apply to allembodiments of the disclosure. It should be appreciated that variationsmay be made to the embodiments described by persons skilled in the artwithout departing from the scope of the present disclosure. Moreover, noelement or component in the present disclosure is intended to bededicated to the public regardless of whether the element or componentis explicitly recited in the following claims.

1. A method for fabricating a backlight source, comprising: determiningan n-step MacAdam ellipse in a uniform chromaticity diagram, n being aninteger smaller than or equal to 3; and fabricating the backlight sourceaccording to chromaticity coordinates within the n-step MacAdam ellipseto cause chromaticity coordinates of light emitted from different onesof light-emitting diodes of the backlight source to be within the n-stepMacAdam ellipse.
 2. The method according to claim 1, wherein determiningthe n-step MacAdam ellipse includes: determining a target colortemperature of a display device including the backlight source;determining an intersection of an isothermal line segment of the targetcolor temperature and a Planckian locus in the uniform chromaticitydiagram; and determining the n-step MacAdam ellipse according to theisothermal line segment and the intersection, the intersection beingwithin the n-step MacAdam ellipse, and two endpoints of the isothermalline segment being on the n-step MacAdam ellipse.
 3. The methodaccording to claim 2, wherein determining the n-step MacAdam ellipseaccording to the isothermal line segment and the intersection includes:determining at least one initial ellipse according to the isothermalline segment and the intersection, each of the at least one initialellipse having the intersection as a center point, and the two endpointsof the isothermal line segment being on each of the at least one initialellipse; matching the at least one initial ellipse with an m-stepMacAdam ellipse in the uniform chromaticity diagram to determine, fromthe at least one initial ellipse, a largest initial ellipse containingthe m-step MacAdam ellipse, wherein n≤m≤7; determining achromaticity-region quadrilateral according to the largest initialellipse, the two endpoints of the isothermal line segment forming afirst vertex and a second vertex of the chromaticity-regionquadrilateral, respectively, a point on the largest initial ellipsecorresponding to a minimum abscissa of the largest initial ellipse inthe uniform chromaticity diagram forming a third vertex of thechromaticity-region quadrilateral, and a point on the largest initialellipse corresponding to a maximum abscissa of the largest initialellipse in the uniform chromaticity diagram forming a fourth vertex ofthe chromaticity-region quadrilateral; and determining the n-stepMacAdam ellipse in the chromaticity-region quadrilateral.
 4. The methodaccording to claim 3, wherein: the light-emitting diodes include atleast two light-emitting diodes that emit white light of differentwavelengths, and the at least two light-emitting diodes have differentred light components, different green light components, and differentblue light components in the emitted white light.
 5. The methodaccording to claim 4, wherein: each two neighboring light-emittingdiodes of the at least two light-emitting diodes emit white light ofdifferent wavelengths.
 6. The method according to claim 4, wherein:among a plurality of chromaticity coordinates of white light emittedfrom the light-emitting diodes in the uniform chromaticity diagram, anumber of chromaticity coordinates located on one side of the Planckianlocus near to a lateral axis of the uniform chromaticity diagram islarger than a number of chromaticity coordinates located on another sideof the Planckian locus farther away from the lateral axis of the uniformchromaticity diagram.
 7. The method according to claim 1, wherein: n isequal to 3, and the n-step MacAdam ellipse has a span less than or equalto approximately 0.01 in a lateral-axis direction of the uniformchromaticity diagram, and has a span less than or equal to approximately0.00978 in a vertical-axis direction of the uniform chromaticitydiagram.
 8. A fabrication apparatus for a backlight source, comprising:a determination device including a processor configured to determine ann-step MacAdam ellipse in a uniform chromaticity diagram, n being aninteger smaller than or equal to 3; and a fabrication device configuredto fabricate the backlight source according to chromaticity coordinatesin the n-step MacAdam ellipse to cause chromaticity coordinates of lightemitted from different ones of light-emitting diodes of the backlightsource to be within the n-step MacAdam ellipse.
 9. The fabricationapparatus according to claim 8, wherein the processor is furtherconfigured to: determine a target color temperature of a display deviceincluding the backlight source; determine an intersection of anisothermal line segment of the target color temperature and a Planckianlocus in the uniform chromaticity diagram; and determine the n-stepMacAdam ellipse according to the isothermal line segment and theintersection, the intersection being within the n-step MacAdam ellipse,and two endpoints of the isothermal line segment being on the n-stepMacAdam ellipse.
 10. The fabrication apparatus according to claim 9,wherein the processor is further configured to: determine at least oneinitial ellipse according to the isothermal line segment and theintersection, each of the at least one initial ellipse having theintersection as a center point, and the two endpoints of the isothermalline segment being on each of the at least one initial ellipse; matchthe at least one initial ellipse with an m-step MacAdam ellipse in theuniform chromaticity diagram to determine, from the at least one initialellipse, a largest initial ellipse containing the m-step MacAdamellipse, wherein n≤m≤7; determine a chromaticity-region quadrilateralaccording to the largest initial ellipse, the two endpoints of theisothermal line segment forming a first vertex and a second vertex ofthe chromaticity-region quadrilateral, respectively, a point on thelargest initial ellipse corresponding to a minimum abscissa of thelargest initial ellipse in the uniform chromaticity diagram forming athird vertex of the chromaticity-region quadrilateral, and a point onthe largest initial ellipse corresponding to a maximum abscissa of thelargest initial ellipse in the uniform chromaticity diagram forming afourth vertex of the chromaticity-region quadrilateral; and determinethe n-step MacAdam ellipse in the chromaticity-region quadrilateral. 11.The fabrication apparatus according to claim 10, wherein: thelight-emitting diodes include at least two light-emitting diodes thatemit white light of different wavelengths, and the at least twolight-emitting diodes have different red light components, differentgreen light components, and different blue light components in the whitelight.
 12. The fabrication apparatus according to claim 11, wherein:each two neighboring light-emitting diodes of the at least twolight-emitting diodes emit white light of different wavelengths.
 13. Thefabrication apparatus according to claim 11, wherein: among a pluralityof chromaticity coordinates of white light emitted from thelight-emitting diodes in the uniform chromaticity diagram, a number ofchromaticity coordinates located on one side of the Planckian locus nearto a lateral axis of the uniform chromaticity diagram is larger than anumber of chromaticity coordinates located on another side of thePlanckian locus farther away from the lateral axis of the uniformchromaticity diagram.
 14. A display device, comprising a backlightsource and a display panel, the backlight source being fabricated by themethod according to claim
 1. 15. A display system, comprising aplurality of display devices according to claim 14.